This invention relates generally to improvements in bar clamps of the portable type in which one of the jaws is usually fixed on one end of the bar and the opposing or cooperating jaw is slidable on the bar toward and away from the fixed jaw. More particularly, the invention relates to such a bar clamp which is adapted to be held in one hand and which has a mechanism for shifting the non-fixed jaw toward the fixed jaw via manipulating the lever on a jaw driving or advancing mechanism.
In its preferred form, the invention relates to a jaw shifting or driving mechanism which may be attached to a commercially available bar clamp to provide a one-hand operable tool in which the shiftable or movable jaw can be advanced or driven by gripping and releasing a lever handle and in which the shiftable jaw can be freed to shift away from the fixed jaw by releasing a brake key.
A bar clamp which requires two hands to manipulate, and which has been commercially available for a number of years, is disclosed in U.S. Pat. No. 2,815,778 dated Dec. 10, 1957 and assigned to Adjustable Clamp Company of Chicago, Ill. Bar clamps which are more or less operable with one hand are disclosed in U.S. Pat. No. 4,926,722 dated Aug. 19, 1988 and U.S. Pat. No. 4,989,847 dated Feb. 5, 1991.
The object of the present invention, generally stated, is the provision of an improved bar clamp that can be operated with one hand. An important and more particular object of the invention is the provision of a mechanism that can be attached to the bar clamp shown and disclosed in U.S. Pat. No. 2,815,778 which converts that bar clamp into a one-hand operable bar clamp. The drive mechanism of the present invention may be readily installed on commercially available bar clamps made pursuant to the disclosure of U.S. Pat. No. 2,815,778.